Preparation of aromatic aldehydes



Nov. 21, 1933. E. T. OLSON PREPARATION OF AROMATIC ALDEHYDES Filed May.18 1933- Smaentor 36,478 7. 0150A/ (Ittomegs Patented Nov. 21, 1933PATENT OFFICE .UNlTED STATES 1'1 Claims.

The present invention relates to the synthesis of aromatic aldehydesfrom hydrocarbons oi the.

benzene series or halogen derivatives thereof and more particularly isconcerned-with the manui'acture oi benzaldehyde from benzene.

Heretoiore in the manufacture of aromatic aldehydes, comparativelyexpensive starting materials have been employed which are treated to arather lengthy and necessarily expensive operation. For example in theproduction of benzalde hyde heretofore, toluene was the startingmaterial which was chlorinated to benzyl chloride and hydrolyzed. Themethod was used to produce benzaldehyde, benzyl alcohol and benzoic acidand employed chlorine, toluene and suitable hy drolyzing acids.

According to the teaching oi the present invention the above enumerateddifliculties and objectional features, are avoided by the provision 01.an improved simplified process which adapts itself I to commercial andcontinuous operation.

Briefly the invention consists in producing aidehydes by treatinghydrocarbons oi the benzene series or halogen derivatives thereof withcarbon monoxide under pressure and in the presence of a suitablecatalyst.

In practicing the invention various forms of apparatus can be employed,however, two forms 01 such apparatus are illustrated in the accompanyingdrawing wherein:

Figure 1 is a cross sectional view illustrating one iorm of apparatusfor carrying out the present invention.

Fig. 2 is a diagrammatic view 0! apparatus for continuously producingaromatic aldehydes as taught in the present invention.

Referring to the drawing the numeral 1 indicates a heavy metalautoclave, which is surrounded by temperature control means, indicatedgenerally at 2, which may comprise an electric resistance coil 3,covered by heat insulating material 4. The autoclave 1 is adapted toreceive a non-corrodible container 7 which is-adapted to slidably fitdown into the autoclave 1 and which may be provided with a flange top 8shaped to fit down against a shoulder portion 9 at the top oi thetank 1. The tank 1 is provided with a cap 12 which may be removablysecured in position by inter-engaging threaded portions 14 upon it andthe tank 1, in which case sockets 15 for the reception of a spannerwrench (not shown) may be provided. A gasket 13 is ordinarily providedbetween the cap 12 and the upper end of the container '7 to insure amore perfect seal. The cap 12 is also formed with a suitably tappedaperture 18 in which is threaded a conduit 17 which extends to a tank 19through the standard con trol valve 21 and pressure gauges 22, 23.

The cap 12 is formed with a threaded central aperture which receives ahousing 26 which in turn 'slidably journals a cylindrical armatureplunger 28'which has a stirring disk 30 secured to its lower end. Theram 28 and disk 30 are of iron or steel and in order to preventcorrosion are suitably plated over with a covering layer 32 or lead,copper, aluminum or other similar nontamishing metals. The stirring disk301s formed with a plurality of apertures '34 which upon verticalreciprocating movement of the ram 28 and stirring disk 30 iunction tothoroughly stir any liquid in the container '1.

In order to reciprocate the stirring disk 30 and the shait 28 whichsupports it, a solenoid coil 36 is provided around the housing 26 andthe relation of parts is such that upon energizing, or de- 45 energizingthe solenoid 36 that the ram 28 and, stirring disk 30 will begiven areciprocating up and down stirring movement in the container 7.

In employing the apparatus above described in the production of aromaticaldehydes the manuiacture oi benaaldehyde is typical and will bedescribed. In this operation, a given quantity 0! benzene and thecatalyst of aluminum chloride, are employed-which quantities havethemolar ratio of aluminum chloride to benzene oi from .2 to I of theformer to 1 of the latter, preferably in the neighborhood of from .33 to.5 of the former to 1 of the latter. These materials are mixed togetherand a certain percentage of water and also a percentage of benzaldehydeis added if necessary or preferred as hereafter described. The completemix is then placed in the container 7, which is in turn lowered into thetank 1 where: upon the cap 12 with the gasket 13 thereunder is screwedinto place to effectively seal the constituents oi the reaction in thetank 1. Thereafter carbon monoxide, which is confined in the tank 19under heavy pressure, is passed by way The temperature is controlled bythe heating means 2 surrounding the tank 1 so as to keep the temperatureduring the mixing operation in the neighborhood. of 25 to 50 C.preferably about C.

The reaction which takes place is as follows:

such as to 3% of benzaldehyde, in the mixture.

of benzene and aluminum chloride prior to the stirring and conversionoperation- Byso doing it has been discovered that the timenecessitatedto reach an equilibrium is considerably reduced, apparently thebenzaldehyde acting in itself as a catalyst. It has been found that thetime can be reduced from approximately two hours to thirty minutes byway of example, if a percentage of the aldehyde to be obtained isinitially mixed in the reaction constituents in the manner described.

.Another important phase of the invention is the addition of a definiteamount of water'to the reacting materials. This water can be added as adefinite measured amount to practically dry benzene, aluminum chloride,carbon monoxide or the amount of water in each one of these reactionconstituents can be determined and the total amount of water present inthe reaction chamber thereby controlled. It has been found thatapproximately 1 liter of water should be used to every 6 kilograms ofaluminum chloride. This ratio when computed on the molar relation ofaluminum chloride and benzene stated above is from about 4% to about 10%of the total weight. The amount of water may be maintained from about0.25% to about 10%.

Referring to Fig. 2 of the drawing, the numerals 40, 41, and 42 indicatea series of autoclaves which are connected together by a plurality ofconduits 46, 48, 50 and 52. A conduit 54 extends to a supply of carbonmonoxide gas which is adapted to be forced by means of a pump 56 throughconduit 58 into autoclave 46, through autoclave into conduit 46, andautoclave 41,

thence through conduit 46 into autoclave 42 from which it escapes to theatmosphere or to a storage or salvage means by way of conduit 60. Aconduit 62 extends to a supply of the liquid reaction products which areforced into autoclave 42 of the system by pumps 64, through autoclave 42into conduit 52, thence'to autoclave 41 and from there to autoclave 40by way of conduit 50. A conduit 66 is provided on the bottom portion ofautoclave 40 to permit withdrawal of the reaction product.

r Check or one way valves may be provided if found necessary ordesirable at the points 70,.72 and 74 or elsewhere in the system.

The apparatus described by-the above and illustrated in Fig. 2 can beemployed in the continuous manufacture of aromatic aldehydes and for thepurpose of example the production of benzaldehyde is typical and will bedescribed.

The benzene and the catalyst, aluminum chloride, are mixed substantiallyin the proportions discussed above under the description of the proc essas employed in conjunction with the apparatus shown in Fig. 1 and thedeterminate amount of water is added whereupon the materials are pumpedby way of conduit 62 and pump 64 to the tank 42 from which they flowthrough conduit 52 into tank 41 and from there by way of conduit intotank 40. Preferably monoxide gas is passed in a counter direction to theflow of liquid constituents through the tank system, as for example byway of conduits 54 and 58, tank 40; conduit 46, tank 41, conduit 48,tank 42 and conduit 60. The carbon monoxide is maintained under thepressure disclosed above by means of pump 56 and arelease valve orpressure chamber isconnected to. conduit as heretofore. described. Thematerials are ordinarily agitated in their passage through theautoclaves either by their "counterflow as by the gas bubbling throughthe liquids or additionally by mechanical means such as those forexample described in conjunction with Fig. 1. 1 1 a The operation ispreferably a continuous one with the reaction products ordinarily beingdrawn oil in a constant manner by way of conduit 66 although this may ifnecessary be a periodic withdrawal. The various features in theoperation of the continuous process are similar to those discussed abovein conjunction with the batch process in that a small amount ofbenzaldehyde is preferably added to the constituents prior to their 105treating, also in that the temperature time and other features aresubstantially within the ranges described.

The products of the reaction of either the continuous or intermittentprocess can be separated to the individual compounds by any suitablechemical or mechanical method such as by hy-.- drolysis anddistillation. More specifically the products of the reaction containingthe anhydrous aluminum chloride catalyst is mixed with water, withcooling. This results in a hydrated aluminum chloride solution whichseparates as a lower layer and can be drawn off from the upper layerconsisting of benzaldehyde and unreacted benzene. This hydration anddissolving of the anhydrous aluminum chloride, which is accomplished ina tank equipped with an agitator and cooling coils, is accompanied bythe evolution of heat. The reaction products may be added to the water,or the water to the reactionproduct, as may be desired.

The benzene in benzaldehyde is separated by fractional distillation. Theseparation by this method is. relatively easy for the reason that theboiling point of benzene is 80 deg. C. while that of benzaldehyde is 180deg. C. Any tars present in the washed benzene-benzaldehyde layer remainas a residue in the bottom of the still. The first fraction that comesoil is a mixture of benzene and moisture,-the moisture being present dueto the hydration process.

The benzaldehyde resulting from the above fractional distillation is apure water white material containing 97 to 99.5% benzaldehyde. It is notsubjected to any further drying or cleaning operation.

While the invention has been particularly described in conjunction withthe production with benzaldehyde for which it is preferably employed itwill be appreciated that'substantially any aromatic aldehydes can bemade from hydrocarbons of the benzene series. in accordance with theteachings of the present invention. For example, toluene can be treatedto obtain p-tolyladehyde,

chlorbenzene can be treated to obtain chlorbenlong as its function incombination with the proc ess is preserved.

What I claim is:-

1. The synthesis of aromatic aldehydes which comprises treatinghydrocarbons of the benzene series with carbon monoxide under pressuresof 350 lb. to 2000 lb. per square inch, in the pres-- ence of aluminumchloride and 0.5% to 3% or the aldehyde.

2. The synthesis of aromatic aldehydes ot'hydrocarbons of the benzeneseries which comprises treating hydrocarbons with carbon monoxide in thepresence 01' a plurality of catalysts and moisture.

3. The method of producing benzaldehyde which includes mixing aluminumchloride and benzene in the molar ratio of from 0.2 to 1 01 the formerto 1 of the latter, adding from .5% to 3% benzaldehyde, subjecting themixture to the action of carbon monoxide at pressures ordinarily between350 lb. sq. in. to 2000 lb. per square inch, and agitating the mixturewhile maintaining it approximately between 20 C. and 50 C. to therebymix the materials and expedite the reaction.

4. The method of producing benzaldehyde which includes mixing aluminumchloride and benzene in the molar ratio of from 0.2 tol oi the former-to1 of thel'atter, adding from .5% to 3% benzaldehyde, subjecting themixture to the action of carbon monoxide at pressures ordinarily between350 lb". sq. in to 2000 lb. sq. in. and agitating mixture.

5. The method of producing benzaldehyde which includes mixing aluminumchloride and benzene in the molar ratio of from 0.2 to 1 of the formerto l of the latter, adding from .5% to 3% benzaldehyde, and subjectingthe mixture to the action of carbon monoxide.

6. The method of producing benzaldehydewhich includes mixing aluminumchloride and benzene in the molar ratio of 1rom 0.2 to 1 of the formerto 1 of the latter, subjecting the mixture to the action of carbonmonoxide at pressures ordinarily between 2501b. sq. in. to 2000 lb. sq.in., and agitating the mixture while maintaining it approximatelybetween 20 C., and 50 C. to thereby mix the materials and expedite thereaction.

7. The method of producing benzaldehyde which includes mixing aluminumchloride and benzene, adding from .5% to 3% benzaldehyde, subjecting themixture to the action or carbon monoxide at pressures ordinarily between350 lb. sq. in. to 2000 lb. sq. in. and agitating the mixture whilemaintaining it approximately between 20 C. to 50 C. to thereby mix thematerials and expedite the reaction.

8. The method of producing benzaldehyde which includes mixing aluminumchloride and benzene in the .molar ratio of from 0.2 to 1 of the formerto 1 of the latter, adding from about i .25% to about 10% water,subjecting the mixture to the action of carbon monoxide and agi-- tatingthe mixture to thereby mix the materials and expedite the reaction.

which consists in mixing aluminum chloride with the hydrocarbon in molarratio of .2 to 1. of the former to 1 of the latter, insuring over .5% ofthe aldehyde intlie mixture, maintaining the presence of between about.25% and about 10% water in the mixture, treating with carbon monoxideunder high pressures and agitating the mixture during the treatment tothereby mix the materials and expedite the reaction.

10. That method of making aromatic aldehydes from hydrocarbons of thebenzene series which consists in mixing aluminum chloride with thehydrocarbon in molar ratio of .2 to 1. of the former to l of the latter,insuring over .5% or the aldehyde in the mixture, treating with carbonmonoxide under high pressures and agitating the mixture during thetreatment to thereby mix the materials and expedite the reaction. v

11. That method of making aromatic aldehydes from hydrocarbons of thebenzene series which consists in mixing aluminum chloride with thehydrocarbon, insuring the presence of from about .25% to about 10% waterin the mixture, treating with carbon monoxide under high pressures andagitating the mixture during the treatment to thereby mix the materialsand expedite the reaction.

12. A continuous method of producing aldehydes from hydrocarbons of thebenzene series which comprises mixing aluminum chloride with thehydrocarbon in molar ratio of between .2 and 1. of the former to'1 ofthe latter insuring over .5% of the finished aldehyde in the mixture,maintaining the presence of between about .25% and about 10% of water inthe mixture, continuously passing said mixture through A a series oftanks, continuously passing carbon monoxide under a pressure or between350 lb.

sq. in. and 2000 lb. sq. in. through the tanks in a direction oppositeto the how of the mixture and continuously removing the reactionaldehyde from the tanks.

13. A continuous method of producing aldehydes from. hydrocarbons of thebenzene series which comprises mixing aluminum chloride with thehydrocarbon in molar ratio of between .2 and 1. of the former to 1 ofthe latter, maintaining the presence 01' between about .25% and about10% water in the mixture, continuously passing said mixture through aseries of tanks, continuously Passing carbon monoxide under a pressureof between 350 lb. sq. in. and 2000 lb. sq. in. through the tanks in adirection opposite to the flow of the mixture and continuously removingthe reaction products from the tanks.

14. A continuous method 0! producing aldehydes from hydrocarbons oi. the.benzene series which comprises mixing aluminum chloride with thehydrocarbon, continuously passing said mixture through a container,continuously passing; carbon monoxide through the container in adirection opposite to the flow or the mixture, insuring the presence ofup to about 10% water in the container and continuously removing the M0reaction products from the container.

15. A continuous method 01' making benzaldehyde which includes the stepsof mixing aluminum chloride and benzene in the molar ratio of between .2and 1.- of the former to 1 of the latter, 14E insuring over .5%benzaldehyde in the mixture, insuring the presence of between about .25%and about 10% of water in the mixture, continuously passing the mixturethrough a series of tanks,

continuously passing carbon monoxide at a pressure between 350 lb. sq.in. and 2000 lb. sq. in. through the tanks in a direction opposite .tothe movement of the mixture, agitating the mixture continuously passingthe mixture through a container, continuously passing carbon monoxide ata pressure between 350 lb. sq. in. and 2000 lb. sq.

in. through the container in a direction opposite to the movement of themixture, agitating the mixture to thereby mix the materials and expeditethe reaction and removing portions of the products formed by thereaction.

17. A continuous method of making benzaldehyde which includes the stepsof mixing aluminum chloride and benzene, continuously passing themixture through a tank, continuously passing carbon monoxide through thetank in a direction opposite to the movement of the mixture, agitatingthemixture to thereby mix the materials and expedite the reaction andremoving portions of the product formed by the reaction.

EDGAR T. OLSON.

